You will certainly move Sweboz nobility there yourself with your FMs as governors. Other well armoured units would be a bit odd because the Sweboz can't afford amour for their own men, how could they for subjugated folk?

Recruitment in Gaul isn't so bad at all: there are the factional spearmen, the excellent slingers and Leuce Epos. And there are the Alps: Teceitos, phalanx, swordfighters. In my Sweboz campaigns I usually recruite the bulk of the army from the Alps, what is also closer to the front both in Itlay and Gaul.

Only the situation in the Belgae lands could be better, given that those people had been very much mixed with Germans.